The present invention relates to a support device for elements protecting rotating shafts, in particular telescopic cardanic shafts.
Currently, mostly due to the codes pertaining to the "CE" mark, cardanic shafts are surrounded by protecting elements which must remain motionless while the shaft rotates at speeds which can reach and exceed even 1000 rotations/minute. The protecting elements therefore must be supported on the rotating shaft by devices that allow their mutual rotation, whilst assuring their positioning. Moreover, the set must be able to be disassembled, for any maintenance operation which may be required, and reassembled.
A currently known support device for such protecting elements is the type wherein a protecting tube is fastened externally to the related telescopic semi-shaft by means of a ring nut, whose inner edge is inserted able slidingly to pivot inside a corresponding groove obtained in the fork of the semi-shaft For this purpose, the ring nut presents circumferential projections which are engaged in corresponding slots obtained in the protecting tube.
Moreover, the ring nut, made of plastic material, presents a through cut to allow it to be widened and then opened in order to insert its inner edge into the groove of the fork and force it to remain therein. The inner edge of the ring nut, which is thus subjected to rubbing, must be lubricated periodically by means of a lubricator.
A disadvantage of this prior art support device consists of the fact that, although the edge is made of plastic material with low friction coefficient, over time it becomes worn. This is also due to the fact that lubrication is not optimal, the edge being discontinuous to allow for the ring nut to be widened during its mounting. Furthermore, the ring nut-fork coupling is exposed to dust and to contaminants in general, with the consequent loss of lubricating grease.
The wear of the ring nut edge leads to the loosening of the shaft-protection coupling, and possibly to its rupture, with the consequent detachment of the elements protecting the telescopic shaft.